Method for coating pipe



May 29, 1945. w. F. FOCHA METHOD FOR COATING PIPE Original Filed Oct.16,1941

BY I v25;

ATTORNEY5 Patented Mr, 29, 1945 METHOD FOR COATING ma William FrancisFocha, Westfleld, N. 1., assignor to Wailes, Dove-Hermiston Corporation,a corporation of New York Original application October is, 1941, SerialDivided an In my Patent No. 2,288,316, June 30, 1942, I have describeda. method and apparatus for coating metal pipe with hot, liquid bitumen.The'apparatus comprises generally a jet ring encircling the pipe andprovided with a plurality of jet oriflees extending about its innerface, The hot liquid bitumen is pumped under pressure from an openair-jacketed sump below the ring, and, through the jet orifices, againstthe pipe in a plurality of fine radial streams, the excess draining backinto the sump. The molten bitumen is poured into the sump at the desiredtemperature and viscosity and maintained in that condition by means ofhot air forced through the annular air-jacket and thence through theair-jacket of the sump. The ring and its connections are supported upona carriage designed to move upon the pipe being coated. Although thismethod and apparatus represent a great improvement over prior methodsand apparatuses for coating pipe with bitumen, some difficulty has beenexperienced in obtainingperfect. coats on the bottom surfaces of thepipe. Excess bitumen flowing from the pipe and dripping from the undersurface congeals, forming projecting teats. Sometimes small craters formbetween the teats and extend through the coat to the pipe itself. Thusdespite the teats, the effective coat on the bottom of the pipe isthinner and of poorer quality than that on the top and sides.

I have discovered that by applying a preliminary coat of bitumen to theunder side of the pipe in advance of the coat applied by the jet ring,the craters are eliminated, the number of teats considerably reduced,and a more uniformly coated pipe is produced. I have found that thispreliminary coat may be applied by means of an auxiliary, multiple jetnozzle lying in advance of the jet ring, but not beyond the forward wallof the sump, through which jets of bitumen are forced upwardly over theunder side of the pipe along a strip extending about 35 on each side ofthe center. Bitumen is supplied to the auxiliary nozzle through anupwardly sloping pipe branching from the pump line just below the jetring.

In the accompanying drawing I have illustrated an apparatus forperforming the method of my invention. In the drawing Figure 1 is a sideelevation of a pipe coating apparatus provided with an auxiliary,multiple jet nozzle, mounted upon a pipe to be coated, and Figure 2 is atransverse section of the apparatus taken along line 2-2 of Figure 1. Inthese figures the driving means for the carriage and the furnace forsupplying hot air to the air-jackets are not shown; nor are (1 thisapplication March 20, 1944, Serial No. 527,223

4 Claims. ('01. 111-94) the air-jackets shown in erence character I.This ring receives molten bitumen from a'sump 2 in which is mounted apump 3 which forces hot liquid bitumen into an annular duct within thering, through a plurality of circumferentially spaced orifices andagainst the pipe 4 which is of metal, usually steel, in a number ofradial jets the excess draining back into the sump. The bitumen in thesump and in the duct is maintained in liquid condition by means of hotair chambers with which both the sump and the ring are provided, as setforth in some detail in my patent. The jet ring and sump are mountedupon a carriage 5 supported and driven by two pairs of wheels 6,designed to run upon th pipe as a trackway. The movement of thecarriage, as it is illustrated in Figure 1 is to the right so that thewheels roll over the uncoated pipe. The foregoing constitutes a briefdescription of the pipe coating machine illustrated in my patent.

In accordance with the present invention I apply a strip of bituminouscoating to the bottom a of the pipe in advance of the main coatingoper-. ation. This is done, when using the apparatus illustrated, bymeans of the jet auxiliary, multiple jet nozzle I extending forwardly ofthe jet ring and below the pipe 4 and supported by a pipe 8 slopingdownwardly from the nozzle to a point of juncture with the pump line.The nozzle 1 is provided with a plurality of upwardly and backwardlyfacing orifices through which jets of bitumen are squirted upon thelower face of the pipe over an are extending approximately 35 on eitherside of the vertical center line of the pipe, as shown most clearly inFigure 2. The hot liquid bitumen is forced through the orifices of thenozzle by means of the pump 3.

Although the jet ring and sump are provided with hot-air jackets tomaintain the bitumen in liquid condition and prevent clogging of the jetorifices of the ring, I have found that the auxiliary jet nozzle neednot be air-jacketed. In its sheltered position below the pipe and abovethe sump, the auxiliary nozzle does not tend to clog and when the pumpis stopped any bitumen in the nozzle and its connections immediatelyflows back into the sump through the downwardly sloping pipe 8. In anyevent, the nozzle and its pipe 8 can be readily detached and cleaned if,for any reason, clogging should occur.

In operation, as the carriage 5 is moved to the right along the pipe 6,as shown in Figure 1, hot liquid bitumen is forced through theauxiliary, multiple nozzle against the bottom of the pipe so that astrip of coating is applied along'the bottom in advance of theapplication of the main coat through the jet ring. This main coat isapplied very soon aftenthe preliminary bottom' coat, and as the jet ringapplies a coat around the periphery of the pipe, the bottom is coatedtwice. While it is not absolutely necessary that the location of thenozzle be such that the material is still hot or semi-liquid when thesecond coat is applied, it is desirable for the reason that it tends tomake for better fusion of the two coats of bitumen and does not permitany foreign substance to come between the two applications. By means ofthis double coating operation it is possible to obtain a substantiallyuniform thickness of bitumen around the full circumference of the pipe.

This application is a division of my application Serial No. 415,273filed October 16, 1941, issued as Patent No. 2,347,316, April 25, 1944,in which I have claimed the apparatus illustrated and described herein.

I claim: I

1. The method of coating metal pipe with hot a plurality of radialliquid bitumen which comprises applying a strip of coating to the bottomof the pipe and then projecting a second coat over the entire peripheryof the pipe.

2. The method of coating metal pipe with hot liquid bitumen whichcomprises applying a strip of coating to the bottom of the pipe and thencoating the entire periphery of the pipe by means of jets.

3. The method of coating metal pipe with hot liquid bitumen whichcomprises applying a strip of coating to the bottom of the pipe by meansof upwardly directedijets, and then applying a coat by means of aplurality of radial jets impinging upon the pipe about its periphery.

4. The method of coating metal pipe with hot liquid bitumen whichcomprises applying a strip of coating to the bottom of the pipe by meansof upwardly directed jets while effecting a relative movement of thepipe and the jets longitudinally of the pipe, and then applying a coatby mean of jets impinging upon the pipe about its periphery, the radialjets being spaced from the strip-applying jets and following them in therelative movement.

' WILLIAM FRANCIS FOCHA.

